Essential Geometry Formulas

Geometry is one of the oldest branches of mathematics, and its formulas come up constantly in calculus, physics, engineering, and everyday life. Here is a reference for the formulas you need most.

2D Shapes

Rectangle: Area = length × width, Perimeter = 2(length + width)

Triangle: Area = ½ × base × height

Circle: Area = πr², Circumference = 2πr

Trapezoid: Area = ½(a + b) × h, where a and b are the parallel sides

3D Shapes

Sphere: Volume = 4/3 πr³, Surface Area = 4πr²

Cylinder: Volume = πr²h, Surface Area = 2πr(r + h)

Cone: Volume = πr²h/3, Surface Area = πr(r + l) where l is slant height

Cube: Volume = s³, Surface Area = 6s²

Pythagorean Theorem

In a right triangle, a² + b² = c², where c is the hypotenuse. This is arguably the most used theorem in all of mathematics. Use our Pythagorean Theorem Calculator to find missing sides.

For quick calculations, try our Area & Perimeter Calculator and Volume Calculator.